The present invention relates to retractable and extendable window shades, and more particularly, to window shades having particular use with the rear window of an automobile.
A rear window shade operating without guide devices is known from EP 0 240 747. With the known rear window shade, the windup roller, which is pre-stressed by a spring, is rotatably seated in a housing on or under the rear-window shelf. The window shade web is fastened by one edge on the windup roller, and its other edge, extending parallel with the first, is connected with a pull rod. The pull rod stiffens the respective edge of the window shade web at the same time.
To unroll the window shade web and to maintain it in the unrolled state, two pivot levers are seated next to the windup roller. The free end of the two rigid pivot levers slidingly engages the pull rod. The window shade web is pulled off the windup roller against the force of a spring by pivoting the pivot levers and is unrolled. At the same time the pivot levers support this edge of the window shade in every operating position and, working together with the windup roller, which is pre-stressed by a spring, keep the window shade web unrolled.
The levers have extensions for pivoting them, which project past the pivot shaft. Coupling rods, which are used as crank arms, act on these extensions, whose other end is also coupled with a crank, which can be selectively caused to rotate by means of an electric motor.
In another embodiment disclosed in the aforesaid reference, a wheel provided with teeth is connected, fixed against relative rotation, with the pivot levers. The teeth of the wheel engage a perforated tape, which is sufficiently rigid to be pushed and is guided in a C-shaped rail. The C-shaped rail must be conducted around the toothed wheel at an appropriate radial distance so that the engagement between the perforated tape and the teeth of the toothed wheel is assured.
In the past, both arrangements have proven well in commerce. However, they do have the disadvantage that the drive motor must be installed approximately in the center between the pivot shafts of the levers, and the crank, on which the rods act, or the respective toothed wheel for the perforated tape, have to be located in the same plane as the toothed wheels of the pivot levers, or their drive cranks. This inevitably necessitates a considerable space requirement at a particular location next to the windup roller.
Based on the foregoing, it is the object of the present invention to provide a window shade, wherein the drive motor can be placed at any arbitrary location.
With the window shade in accordance with the invention, the drive mechanism for the actuating element is operatively connected with the actuating element via flexible coupling means. Because of this it is possible to select the position of the respective drive mechanism, an electric motor as a rule, freely inside the vehicle. It is no longer necessary to house the drive motor between actuating elements in the form of the pivot levers. Instead, the drive motor can be mounted set apart in a side area of the vehicle, where its housing has sufficient space because of the hollow spaces which necessarily exist between the outer body and the inner paneling. It can also be arranged on the other side of the windup roller.
Although as a rule the connection between the coupling means and the respective actuating element is selected in such a way that essentially tensile forces occur in the coupling means, pressure forces are unavoidable at the end of the retracting movement. In the course of the retracting movement of the window shade, the spring drive of the windup roller acts in the direction wherein the respective actuating means are pivoted back into a position, in which the actuating means essentially lie parallel with the windup roller. The drive motor only needs to provide a small pulling force for this pivot movement, if the levers still extend comparatively steeply, i.e. at right angles in respect to the windup roller. The pulling force changes into a pushing force toward the end of the pivot movement, if care is taken that the pivot levers are completely pivoted back into the position of rest. In the course of this it may be necessary to overcome a resistance which is created when rollers attached to the pull rod pass by the housing slit of the window shade. The rollers are intended to prevent damage to the heating wires on the inside of the rear window. The restoring force of the spring in the windup roller is not sufficient for them to move past the slit edge, it is instead necessary to fold the levers back by the force of the drive motor.
Depending on the embodiment, the mechanical blockage of a further pivot movement achieved after folding them back is also used for stopping the motor. Subsequently the motor current is automatically switched off after a preselected period of time, or it is switched off if its value exceeds a preselected threshold.
So that the flexible coupling means do no become kinked under a pressure load, kink-protection means are additionally provided and are used for guiding a section located on one end of the core and extending out of the flexible sleeve in a manner secure against kinking in every operational position.
Depending on the design, the anti-kinking guidance can be provided in the area of the actuating element, as well as in the area of the drive mechanism. Particularly in the case, where the electromechanical drive device, which is connected with the coupling means, operates with the aid of a crank drive, it is practical when the core is provided with such kink-protection means on both ends of the coupling means.
Different structures may embody the kink-protection means. In one embodiment, the end of the core is rigidly connected with a tube, through which the core is coaxially conducted, and which extends over the sleeve of the Bowden cable. In order to achieve the desired guidance action, the sleeve of the Bowden cable can be rigidly designed in any area where this stiffening tube extends over the sleeve. In this case the sleeve and the tube connected with the core act like a telescope. The stiffened end of the sleeve in this instance can also be an individual rigid tube. The sleeve of the Bowden cable is attached to one end of this tube.
Alternatively,the end of the core itself may be rigid. To this end, the core can terminate in a rigid or kink-resistant rod, which is appropriately guided.
For moving the core back and forth, the core can have teeth, for example at the end toward the motor, which are engaged by a toothed wheel of the drive motor.
Either simple levers, whose free ends slidingly engage the pull rod, are used as actuating means for unrolling the window shade web, or toggle levers, whose free end is connected with the pull rod via a hinge shaft. The one-piece levers, as well as the inner toggle lever arm, have an extension projecting past the pivot shaft, on which the coupling means act. By means of this the coupling means may remain inside the housing in every pivoted position of the actuating element, i.e. remain covered by the slit.
As in the prior art, a spring, which is coupled, fixed against relative rotation, with the windup roller, can be used to put the windup roller into motion. The windup roller is pre-stressed in the winding direction of the window shade web by means of the spring.
Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which: